This invention relates to a clamping structure and the method for clamping together the mold sections of a mold unit to form a sealed mold cavity and, more particularly, to a clamping structure and method for transmitting or distributing the mold clamping force uniformly over the coacting cavity sealing portions of the mold sections.
Injection molding machines generally include a two-section mold unit wherein one of the mold sections is stationary and includes an ingate opening for the injection of mold material into the mold cavity. The other mold section is movable between an open position away from the stationary mold section and a closed position wherein the two mold sections are in sealed contact engagement to form the mold cavity. When mold material is injected under high pressure into the mold cavity, the two mold sections must be in a positive sealed engagement to prevent the escape of mold material from the mold cavity. Conventional injection molding machines typically apply a linearly directed hydraulic force only on the central portion of the movable mold section. This method of applying a mold clamping force generally results in a distortion of the movable mold section so as to require a relatively high pressure to seat only portions of the cavity seating surfaces of the mold sections.